(1) Field of the Invention
This invention relates to electric motors and is directed more particularly to an improved stator for a disc type electric motor.
(2) Description of the Prior Art
Disc type electric motors are known in the art. Such motors typically include two stators and, positioned therebetween, a rotor. Motors of this type are usually of compact size and exhibit, for their size, high power density and high power output. Such motors are often found in products such as camcorders, VCR machines, and CD/CD-ROM machines.
A typical stator for such motors comprises a ferromagnetic body which is provided with a slotted disc portion having radially extending slots facing the rotor. The ferromagnetic stator further includes a non-slotted disc portion outboard of the slotted disc portion and integral therewith or attached thereto. Insulated electrically conductive wires are wound upon the slotted disc portion through the slots therein. The wire windings are energized to form a rotating magnetic field, causing the rotor to rotate.
Increasing the current in the windings increases the magnetic force generated by such stators until magnetic saturation of the stator is reached. Thereafter, increases in winding current does not result in an appreciable increase in magnetic force. Further, alternating current flowing through the windings causes the wires to move repeatedly toward and away from the stator because of the repeated changes in the magnetic field attracting the wire. Such continuous movement, in conjunction with the build-up of heat in and about the windings, results in insulation failure leading to shorts between the winding and the stator.
Accordingly, there is needed an improved stator which is not limited by magnetic saturation, is not as subject to shorting, and provides for improved transfer of heat produced by the windings.